Direct observation of growth and melting of the hexagonal-domain charge-density-wave phase in 1T-${\mathrm{TaS}}_2$ by scanning tunneling microscopy

A variable-temperature scanning tunneling microscope has been used to elucidate the structure of the nearly commensurate (NC) charge-density-wave (CDW) phase in 1T-${\mathrm{TaS}}_2$. Between 230 and 350 K the NC CDW phase consists of a hexagonal array of commensurate domains separated by diffuse domain walls where the CDW phase and amplitude change. The average domain period and size increase continuously as the temperature is lowered over this range. Microscopic details of this growth process are discussed.